Question

What is the speed in km/h if the distance is 500 metres and time taken = 100 seconds ?

Answer 1

`18 \ "km/h"`

Explanation:

Well, the speed in `"m/s"` is

`(500 \ "m")/(100 \ "s")=5 \ "m/s"`

An important conversion factor is that

`1 \ "m/s" = 3.6 \ "km/h"`

So, the speed in `"km/h"` is `3.6*5=18 \ "km/h"`

Answer 2

I tried this:

Explanation:

We evaluate the speed as usual as:
`"speed"=v="distance"/"time"`
giving:
`v=500/100=5m/s`
BUT we need it in `(km)/h`; we know that `1km=1000m` so that `1m=1/1000km` and `1h=60xx60=3600s` (`60min` in one hour and `60s` in one minute) so that `1s=1/3600h`.
Let us use these information into our velocity:
`v=5m/s=5(1/1000km)/(1/3600h)=5*3600/1000(km)/h=5*3.6(km)/h=18(km)/h`